Introduction | SNMP Architecture | the Protocol
Structure of Management Information | Object Identifier
Management Information Base | Common Tasks | References

Object Identifier

OID (Object Identifier) is a data type used to identify an object in the data structure. It is a sequence of integer numbers, separated by decimal points who indicates what edge should be selected in the data tree structure to find an object, like in the figure below:

To simplify the human read, is common to use the name corresponding to the studied object, like 1.3.6.1.2.1.2. The mentioned object can be found using the object identifier iso.org.dod.internet.mgmt.mib.interfaces.

To access a simple variable, should you insert a ".0" to the object identifier like the variable
1.3.6.1.2.1.1.1.0(iso.org.dod.internet.mgmt.mib.system.sysDescr.0).

In a table access, you should insert one or more INTEGER's to represent the object's row, and, after it, it's object identifier, like in
1.3.6.1.2.1.7.5.1.1.127.0.0.1.67 (iso.org.dod.internet.mgmt.mib.udp.udpTable.
udpEntry.udp LocalAddress.10.0.0.1.67
or, to simplify, udpLocalAddress.10.0.0.1.67). In this case, the udpLocalAddress of the entry 10.0.0.1.67 will be returned. Note that 10.0.0.1 is an IP of a connection and 67 the used port. Both are collumns of the table. More information can be obtained in the udp group.